1. Field of the Invention
The present invention relates to a transcutaneously implantable element in which at least a portion thereof in contact with a cutaneous tissue is composed of a ceramic material comprising, as the main raw material, at least one member selected from the group consisting of hydroxyapatite, tricalcium phosphate, and tetracalcium phosphate.
2. Description of the Prior Art
Transcutaneously implantable elements such as a percutaneous electrode connecter or a cannula are used as an electrical terminal for collecting biological information such as blood pressure, flow rate of blood, temperature, and electrocardiosignals, or as a port for taking and injecting blood through the through hole thereof, for example, as a port for effecting transfusion, injection of liquid medicines, or artificial kidney dialysis. When these transcutaneously implantable elements are used, one end of the element is placed on the skin of a living body and the other end thereof is buried under the skin. Conventional transcutaneously implantable elements already proposed are mainly composed of a so-called bioinactive material, for example, a silicone rubber or a fluorine-contained resin.
However, strictly speaking, these transcutaneously implantable elements are only extraneous substances to a living body, and a portion of the living body in which the element is mounted is in a traumatized state. Therefore, bacterial infection may be caused from the interstice between that portion and the element. Accordingly, these transcutaneously implantable elements cannot possibly withstand a long period of service. Furthermore, the transcutaneously implantable elements involve problems in that since they cannot be firmly implanted in the living body, bleeding may occur due to, for example, shaking, and since noise such as a so-called artefact cannot be eliminated when bioelectrical signals, for example, electrocardiosignals, are collected, bioinformation cannot be stably gathered. Therefore, the transcutaneously implantable elements have not been widely accepted.
For example, with a so-called drug delivery system for an artificial pancreas or the like (see Kraus Heylman, "Therapeutic Systems" published by Georg Thieme Publishers, 1978) recently developed rapidly, the problems of the injection route and the infinitesimal quantity quantitative injection of drugs such as insulin have not been solved as yet (Medical Instrument Society Journal, Vol. 53, No. 2, 1973, infra p. 90). Therefore, there is now an increasing demand for a transcutaneously implantable element which can be semi-permanently and safely used as an injection inlet for drugs.
On the other hand, as the excellent bio-compatibility and bone-deriving ability of sintered bodies of hydroxyapatite, tricalcium phosphate or the like have been clarified recently, the utilization of these sinters as an artificial dental root or an artificial bone has been proposed and practically effected. However, the physiological reactivity of the sinters to the cutaneous tissue of a living body has not been solved in the prior art.